Clover is in the genus Trifolium which represents nothing more than its three leaved growth habit.. Some people refer to it as trefoil. The trefoil or sometimes triquetra is an ancient symbol found in many cultures. Most famous perhaps in its use as the so-called Celtic knot. In knot theory, yes there is a branch of mathematics that deals with knots (topology), the trefoil is considered a nontrivial knot. In geometry the trefoil is the intersection of three circles. The center of those circles in the well-known (nontrivial) Celtic knot. In architecture the trefoil arch is the familiar arch in many cathedrals. Of course the trefoil came to be used in many medieval manuscripts to represent the Christian trinity. Such is the trivial life of the clover.